An auxiliary power steering system is known from DE-PS (German patent) 1,750,263. Such design is disadvantageous in case of reversal of the steering direction when the servopiston is to be reversed from the end of a power stroke in an opposite steering direction toward the direction of neutral position. The initial movement must take place without auxiliary power support but by human force on the manual steering wheel. Only after the servopiston has been reversed a distance toward neutral position can flow connection between the two working chambers of the servocylinder be interrupted and servopressure used to reverse the servopiston.